1. Technical Field
The present disclosure relates to a wafer inspecting method and, more particularly, to a wafer inspecting method that is used for inspecting a defect of a wafer.
2. Discussion of Related Art
Yield improvement is very critical in a semiconductor device fabricating process. In this regard, many different methods for achieving yield improvement have been suggested and carried out.
For example, a wafer inspection process is performed whenever each unit process for fabricating the semiconductor device is completed.
A wafer inspection process that inspects the exterior of a wafer is performed to determine whether to proceed with the next process, by checking the state of the wafer upon completing each unit process. The wafer inspection process is performed by using a wafer inspecting apparatus, such as a microscope.
FIG. 1 is a view useful in explaining a conventional wafer inspecting method.
As illustrated in FIG. 1, the conventional wafer inspecting method is performed by first predetermining a unit inspection region, such as a cell or a die, and then comparing a scanned image of a pattern image in a normal state of the predetermined unit inspection region, hereinafter referred to as a “reference image”, with a scanned image of a pattern image to be inspected in the predetermined unit inspection region hereinafter referred to as a “detection image”.
When the reference image is different from the detection image, a difference of the images, that is, a difference image, is detected as a defect, as illustrated in FIG. 1.
In the conventional wafer inspecting method, however, noise including a pattern discoloration or a pattern brilliance, which do not affect the yield of a semiconductor device are detected as a defect of a wafer. More specifically, when a multilayer device such as a metal layer is inspected using the conventional method, not only a defect to be detected but also noise, such as pattern brilliance or grain reflecting light by crystals generated from metal particles, are detected as defects.
Consequently, since the conventional wafer inspecting method also detects noise when a defect of a wafer is detected, it is impossible to determine which portion of the wafer is weak and causes the defect, from a may displaying detected result.